A photoelectron spectroscopy study of tunable charge injection barrier between metal/organic interface

Photoelectron spectroscopy has been used to investigate a tunable charge injection barrier at the metal/organic interface. Results in this study show that the morphology of the Al electrode in the indium tin oxide (ITO) LiFAl /pentacene structure plays a critical role. When the sample is biased across ITO and Al electrodes, shifts in the binding energies of certain core-level electrons are observed on the surface of the discontinuous thin Al electrode. In contrast, no such shifts are observed on the thick Al electrode. Further studies indicate that applying a voltage bias changes the energy alignment between the discontinuous thin Al electrode and the pentacene layer deposited on it.